基于开放光路离轴积分腔的甲烷传感技术与实验
摘要
Objective: Methane (CH<sub>4</sub>) is the main component of natural gas; it is a kind of colorless, odorless, flammable, and explosive gas. It has major safety hazards in natural gas transportation and coal mining. The demand for natural gas has gradually increased recently. Generally, natural gas is transported to various areas through pipelines, and the aging of pipelines may cause leakages, which will cause long-term CH<sub>4</sub> emissions, resulting in severe environmental problems and huge energy waste. In a closed environment, CH<sub>4</sub> leakage is difficult to detect, which leads to potential hazards, such as suffocation and explosion. For example, in factories, coal mines, and other places, when the CH<sub>4</sub> concentration in the environment reaches a certain limit (5%17%), an explosion will occur, leading to severe safety accidents. Therefore, real-time and accurate CH<sub>4</sub> concentration detection in the production environment is paramount to ensure life safety and reduce economic losses. In this study, a near-infrared sensor system based on the open-path off-axis integrated cavity output spectroscopy (OA-ICOS) technique was proposed for fast and real-time atmospheric CH<sub>4</sub> concentration detection. Further, simulated CH<sub>4</sub> leakage detection and the performance of the sensor system were verified through gas sensing experiments. Methods: CH<sub>4</sub> detection methods include catalyst combustion, electrochemistry, and infrared laser absorption spectroscopy. Infrared laser absorption spectroscopy is widely used because of its in situ quantification. OA-ICOS is a type of laser absorption spectroscopy and has received enormous attention recently due to its long optical path (OP), high robustness, and other advantages. In this experiment, the OA-ICOS technique was used to detect CH<sub>4</sub> in real time based on an open OP design. A tunable semiconductor laser with a center wavelength of 1653 nm was used as the light sour